The invention relates to an interrupter device of the hybrid type for high or medium voltage. The term xe2x80x9chybridxe2x80x9d applies to interruption which is of the combined type in which two different interruption techniques are caused to co-operate. The term xe2x80x9chybridxe2x80x9d is used in particular to designate an interrupter device that comprises both a vacuum interrupter containing a first pair of arcing contacts, and also a gas interrupter containing a second pair of arcing contacts.
A device of this type is known from U.S. Pat. No. 3,038,980. It comprises a casing filled with a dielectric gas and having a longitudinal axis. The two interrupters are connected electrically in series and are disposed inside the casing, while the control mechanism for controlling the device is disposed outside the casing. The mechanism for actuating the contacts of the two interrupters is relatively simple in that one of the two contacts of the gas interrupter is secured to a moving contact which is adjacent to it in the vacuum interrupter. The other contact of the gas interrupter is secured to a drive rod connected to the control mechanism for controlling the device. A mechanism having a spring associated with an abutment maintains the contacts of the gas interrupter one against the other during a first portion of their stroke while the device is opening, until the contacts of the vacuum interrupter have separated by a determined distance. The object of such a sequence for separating the contacts of the two pairs is to make it possible to delay the separation of the contacts of the second pair (gas interrupter) relative to the separation of the contacts of the first pair (vacuum interrupter).
Unfortunately, such a sequence is not satisfactory if the high-voltage hybrid device associates a gas interrupter designed for a standardized high voltage higher than 72.5 kV with a vacuum interrupter designed for a standardized medium voltage lower than 52 kV. So long as the contacts of the gas interrupter have not separated while the device is interrupting a fault current, the vacuum interrupter is subjected to the entire transient recovery voltage across the terminals of the interrupter device while its contacts are separating. Unfortunately, the vacuum interrupter is designed to withstand only a recovered voltage that remains within medium voltage limits. Thus, a high-voltage hybrid interrupter device that implements the above-described sequence for separating contacts can interrupt the current only after the two contacts of the gas interrupter have separated. Such operation involves an arcing time that is relatively long, and that is longer than the time a vacuum interrupter is designed to withstand. The general structure of the device described in that U.S. Pat. No. 3,038,980 does not make it possible to modify the sequence for separating the contacts. In particular, it is not possible with such a device to obtain simultaneous or delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter.
Another device of that type is known from patent application EP 1 109 187, which enables the sequence for separating the contacts to be adjusted so as to be able to obtain simultaneous or slightly delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter. The moving contact of the vacuum interrupter is connected to a connecting rod having one end that rotates, the end or head of the connecting rod being hinged on a crank pin of a flywheel that can be coupled to or uncoupled from a toothed rod controlled in translation by the drive rod of the gas interrupter.
However, that device presents certain drawbacks from a mechanical point of view. Firstly, it is necessary to exert sufficient force on the moving contact of the vacuum interrupter so long as current is able to pass therethrough, so as to ensure mutual pressure between the contacting surfaces of the contacts of the interrupter which is greater than a given value in order to overcome the electrodynamic forces generated by the passing current. The flywheel of the device must therefore be provided with a resilient return system which enables the required force to be exerted on the moving contact of the vacuum interrupter. Secondly, the motion of the drive rod of the gas interrupter is transmitted towards the vacuum interrupter by a connecting rod having an axis that is oblique relative to the axis of translation of the moving contact of the vacuum interrupter. That results in significant transverse stresses on the vacuum interrupter, thereby limiting its mechanical endurance.
Finally, another device of this type exists which is described in patent application EP 1 117 114, and which compared to the previous device has, in particular, the advantage that the moving contact of the vacuum interrupter is always subjected to forces that are directed only along the longitudinal axis of the interrupter. In addition, resilient spring means are provided to maintain a mutual pressure between the contacts of the vacuum interrupter while the interrupter is closed. However, in that device, the separating movement of the contacts of the vacuum interrupter is under the control of the drive rod of the gas interrupter, so the contacts of the vacuum interrupter can be separated only once the contacts of the gas interrupter have been opened. It is necessary for that device to have such a sequence of deferred separation of the contacts so as to cause the current to pass through zero before the vacuum interrupter ensures interruption on its own. The device is used exclusively as a generator circuit-breaker, and consequently, the gas interrupter is present only to reduce the unbalanced fraction of the current.
Obviously, with that device, it is not possible to produce simultaneous or slightly delayed separation of the contacts of the vacuum interrupter relative to the separation of the contacts of the gas interrupter.
An object of the invention is to remedy the drawbacks or limitations of the prior art, by providing a hybrid interrupter device for high or medium voltage that is relatively compact and longlasting, and that when operating with a single drive member, i.e. with a control mechanism connected to a single drive rod, enables the interrupter contact separation sequence to be adjusted.
To this end, the invention provides a hybrid-type interrupter device for high or medium voltage, the device comprising:
a casing filled with a dielectric gas and having a longitudinal axis;
a vacuum interrupter disposed inside the casing, and having a first pair of arcing contacts constituted by a first contact which is fixed and by a second contact which can be moved in translation in the longitudinal direction of the casing;
means provided to exert a force on the second contact such that the mutual pressure between the contacting surfaces of the first and second contacts is greater than a determined value while the vacuum interrupter is allowing current to pass;
a gas interrupter disposed inside the casing, and having a second pair of arcing contacts constituted by a third contact which is fixed and by a fourth contact which can be moved in translation in the longitudinal axial direction, and also having a blast chamber which comprises a thermal blast volume; and
a drive rod connected to the fourth contact and that can be held stationary or moved in translation by control means;
the device further comprising;
connection means electrically interconnecting the second and third contacts, and capable of being moved in translation in the longitudinal axial direction together with the second contact;
displacement means connected to the connection means and to the drive rod for displacing them so as to separate the second and fourth contacts from the first and third contacts respectively, said displacement means comprising dead-stroke link means connecting the connection means to the rod, the link means making it possible to displace the rod over a determined dead stroke while also acting on the connection means to keep the vacuum interrupter closed during this displacement.
Advantageously, for applications where a device of the invention is intended to be used as a circuit-breaker in a high-voltage network, the displacement means are organized so that the separations of the contacts both of the vacuum interrupter and of the gas interrupter take place simultaneously or with a small offset in time. This enables the transient recovery voltage which appears between the contacts of each interrupter as soon as they separate to be shared appropriately between the vacuum interrupter and the gas interrupter.
For applications where a device of the invention is intended to be used as a generator circuit-breaker for a medium-voltage network, the displacement means are preferably organized so that the separation of the contacts of the vacuum interrupter is substantially delayed relative to the separation of the arcing contacts of the gas interrupter, so that the gas interrupter causes the current to pass through zero before the vacuum interrupter interrupts the current.
In particular embodiments implementing said dead-stroke link means, an interrupter device of the invention may comprises one or more of the following characteristics taken in isolation or in any technically feasible combination:
the dead-stroke link means comprise return-movement means which co-operate with first resilient means connected to the connection means or to the drive rod;
the displacement means comprise second resilient means suitable for co-operating with the connection means for separating the contacts of the vacuum interrupter as soon as the drive rod has traveled over said dead stroke, and suitable for displacing the connection means and the second contact over a determined isolation stroke relative to the first contact while the device interrupts current, the isolation stroke corresponding to the complete separation distance of the contacts of the vacuum interrupter;
the first and second resilient means respectively comprise a first and a second spring each compressed and suitable for extending with a determined extension, said springs co-operating respectively with first and second abutment means each suitable for interrupting the relaxation of the spring with which it co-operates, each spring exerting thrust on the connection means along the axis, and the two springs exerting thrust in opposite directions;
said first abutment means are secured to the connection means;
said second abutment means are connected to the third contact, and provide the electrical connection with the connection means;
said return means comprise two portions suitable for being displaced together in mutual abutment, and suitable for being dissociated during opening of the vacuum interrupter; and
a first portion of said return means is subjected to a thrust from the first resilient means which makes it possible to displace said portion over said dead stroke relative to the connection means, a second portion of said return means being constrained to move in translation with the rod.
In a first embodiment of an interrupter device of the invention, the contacts of the gas interrupter are interfitted one in the other when in the closed position, with an overlap distance that is less than or equal to the dead stroke that can be traveled by the first portion of the return means along the connection means.
In a second embodiment, of an interrupter device of the invention, the contacts of the gas interrupter are in mutual abutment in the closed position, and delay means for delaying the start of movement of the fourth contact are interposed between said fourth contact and the drive rod for actuating the device. In a variant of this second embodiment, the drive rod and the third and fourth contacts are tubular in shape along the axis, and said delay means comprise:
a first tubular element that is disposed in axial alignment with the fourth contact, that is secured thereto, and that can slide inside the rod while said rod is being displaced, the sliding distance being less than or equal to said determined dead stroke;
third abutment means fixed to an end of the first tubular element where it is connected to the fourth contact;
a second tubular element that is secured via one end to the second portion of the return means, that is of diameter greater than the diameter of the first tubular element, that can slide along the third abutment means along the axis while the rod is being displaced, and that is provided at its other end with an annular cap serving to come into abutment with said abutment means; and
a helical third spring disposed along the axis, interposed between the first tubular element and the second tubular element, in abutment at one end against the third abutment means and at the other end against the second portion of the return means.
Each of the third and fourth tubular contacts may have its end provided with an end-piece made of a refractory conductive material.
For the two above-mentioned embodiments, an interrupter device of the invention may comprise one or more of the following characteristics taken in isolation or in any technically feasible combination;
the connection means are constituted by a metal socket that is circularly symmetrical about the axis, said socket having a hollow tubular portion which, at its open end, has a first annular shoulder that constitutes the first abutment means;
the metal socket has a cylindrical portion in which an annular recess is provided that is open facing towards the vacuum interrupter and that serves to receive the second spring, the wall that surrounds said annular recess optionally having, at its end, a second annular shoulder for holding the first spring in abutment;
in order to enable the return means to be moved in translation along the connection means, the first portion of the return means has, at one end, an annular wall which comes into abutment against an end of the first spring, the inside diameter of said annular wall being equal to the outside diameter of the tubular portion of the socket;
the second abutment means are constituted by a cylindrical stud fixed to the third contact and disposed in axial alignment therewith, the metal socket being engaged over said stud and being mounted to slide therein while also providing permanent electrical contact therewith, the hollow tubular portion of said socket having an end-wall serving to come into abutment against said second abutment means;
the magnitudes of the thrusts of the first and second springs are organized to have, at all times, a difference in favor of the magnitude of the first spring, this difference remaining continuously greater than a determined threshold;
the second of the two portions of the return means is electrically connected permanently to a terminal and supports a sliding contact serving to be in electrical contact with a conduction element when the interrupter device is closed;
said conduction element is fixed to the connections so as to be electrically connected permanently to the second contact of the vacuum interrupter;
a varistor is electrically connected in parallel with the contacts of the vacuum interrupter in order to make it possible to limit the voltage applied to said vacuum interrupter, so as to distribute appropriately the voltages applied to the vacuum interrupter and to the gas interrupter during opening of the interrupter device; and
a capacitor is mounted in parallel with one of the interrupters or in parallel with each of the interrupters for the purpose of obtaining said appropriate distribution.